This is as vague as a problem report can be, so here goes nothing. I've been running the SD kernel on my N810 since the first version with working WPA2 version with little trouble. Today, however, was quite different: the screen wouldn't blank.

On my way to work this morning, I used my N810 to run Anki, just as I usually do. My device automatically logged in to WLAN in the tram, just as it usually does. When I got to work I was in a hurry to test some things online. Instead of having my device connect automatically to our office WLAN, I opened connection dialog and accidentally chose BT connection. I quickly disconnected and connected to WLAN instead. Something clearly went wrong as I didn't receive any DNS server IPs. I tried to switch back to BT connection but this also failed. Connection problems like this are nothing uncommon, so I routinely rebooted. After rebooting everything was back to normal -- or so I thought.

After finishing things I needed to check I started working on things I get paid to work on. After a few minutes I noticed that display of my device was still on. I SSHd to the device and checked if there was anything interesting in kernel log. Nope. I restarted systemui to see if that helped. Nope. I tried running advanced-systemui to see if that helped. Nope. I went to control panel to see if adjusting screen brightness worked. Yup, that worked, but ambient light sensor would only dim the screen. I rebooted again (twice) and noticed that while the screen backlight was not turned off, screen updates would not take place after leaving the device idle for awhile. This was easy to spot by having top running on SSHd connection and load applet running in status bar, as the two would show different data. Running out of ideas, I uninstalled DT and rebooted with community SSU kernel to see if /that/ helped. Indeed, that solved the display issue.

This is odd. Apart from initial issued and "delayed" screen updates after turning on the display, I have had minimal trouble with DT SD kernel -- until today. Today this problem caught me completely off-guard, and I have no idea what is going on. As there was absolutely nothing in kernel log, I have nothing to go on with.

I will switch back to DT kernel when I can, but since I have to be able to depend on my device for next ~ten days, it'll have to wait.